Promethium-147 (also written as Pm-147, 147 Pm) has been of commercial and research interest for many years for use as a beta source for thickness gauges or for luminescence devices to produce light, such as watches, signs, etc. Promethium-147 decays with beta minus (β−) process with a half-life of 2.6 years to the stable samarium-147 (Sm-147). In 99.994% of time, promethium-147 decay feeds to the ground state of Sm-147 and, consequently, the decay of promethium-147 is followed by emission of an extremely week gamma-ray at 121 keV with an intensity of only 0.00285%. The maximum energy of the β− particles from promethium is 224.5 keV, with an average energy of ˜62 keV.
Light produced from luminescence devices using promethium-147 is used for visual devices and to produce signals which required dependable operation. Such technology has been used for nuclear powered batteries by capturing light in photocells which convert the energy into an electric current. Promethium-147 batteries have a useful shelf life of about five years. Promethium-147 also shows promise as a heat source and auxiliary power source for satellites and space probes. Conventionally, promethium-147 has been isolated in large amounts from uranium-235 fission products. Until the 1970's, Oak Ridge National laboratory (ORNL) had a large inventory of about 853 grams of promethium-147 which had been isolated from fission products at the Hanford, Wash., nuclear facility. Fission products are no longer processed in the U.S. because such processing is exceptionally expensive and produces very high levels of long-lived radioactive wastes. The ORNL inventory has long been exhausted, and there is currently no domestic source of significant amounts of promethium-147. There is therefore a need for a promethium-147, but from a different, available, environmentally safer source; the present invention addresses that need.